High-voltage ignition system for internal combustion engines



Jun@ Z0, WW D. sTmBERvL-s .ET/M 33279354 HIGH-VOLTAGE IGNITION SYSTEM TOR INTERNAL COMBUSTION ENGINES Filed Jan. l5, 1965 3 Sheets-Sheet l 11m@ 20, W57 D. STEINBERG UAL 3,32754 HIGH-VOLTAGE IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 15, 1965 3 sheets-sheet. 2

`Fume 20, 1967 D. sTExNB-:RG ETAL 3,327,64

INTERNAL COMBUSTION ENGINES HIGH-VOLTAGE IGNITION SYSTEM FOR 5 Sheets-Sheet 5 Filed Jan. l5, 1.965

United States Patent O 3,327,164 HlGH-VGLTAGE EGNTHON SYSTEM FR INTERNAL COMBUSHON ENGENES Diedrich Steinberg, Stuttgart, Gerhard Shner, Geradstetten, Kreis Waibiingen, and Jrg lssler, Stuttgart, Germany, assignors to Robert Bosch GJrLb-L, Stuttgart, Germany Filed ian. 13, 1965, Ser. No. 425,303

Claims priority, application Germany, Jan. 18, 1964,

11 Claims. (Cl. 315-200) ABSTRACT F THE DESCLSURE The invention relates to a rectifier controlled high-voltage ignition system having a diode and resistor in 4parallel connection between the control electrode of the rectifier and a storage system connected to one pole of the source.

This invention relates to a high-voltage ignition system for internal combustion engines, and, more particularly, to a control device for controlling a transistor ignition system. In systems of this type, a semiconductor device is connected in series with the primary winding of an ignition coil and a source of direct current, which is usually the battery of the internal combustion engine, and a device for controlling the semiconductor device is provided which operates at a cyclic frequency determined by the speed of the engine.

In presently known high-voltage ignition systems of this type, transistors are provided in place of the previously used cam-actuated circuit breakers. These transistors are connected in series with the primary winding of the ignition coil; at the instant of ignition, the transistor is switched to its blocked state, interrupting the current in the primary ofthe ignition coil. During this process, a substantial inductive voltage peak is generated across the transistor, necessitating the use of special measures to protect the transistor against voltage breakdown.

In another known system, a capacitor is used in conjunction with semiconductor thyratrons, the voltage sensitivity of which is substantially less. However, in this type of system the semiconductor thyratrons are generally connected, together with the primary winding, in the discharge circuit of a storage capacitor supplying the ignition energy. The storage capacitor is charged between sequential ignitions and discharged during ignition.

It is therefore an object of the present invention to provide an ignition system for an internal combustion engine which is free from the drawbacks involved in prior art systems.

It is a further object of the present invention to provide an ignition system for internal combustion engines in which the ignition energy for the engine is supplied by the electromagnetic ield in an ignition coil, the primary winding of which is controlled by a thyristor, and in which an energy storage element is provided for controlling the thyristor.

These objects as well as others are achieved in a coil ignition system of the type described in the introduction, in which the ignition energy is supplied by the electromagnetic lield of the ignition coil, by providing a semiconductor thyratron-or thyristor-particularly a silicon thyristor, as the semiconductor device, which thyristor is connected by its two primary electrodes in series with the primary winding of the coil. This thyristor can be switched in by a positive control voltage at its control electrode and can be switched oil by a negative control voltage. Furthermore, an electrical energy storage element, such as a capacitor, and/or an electromagnetic energy storage element, such as an iron-cored choke coil, is provided in a circuit connected in parallel to the control electrode and a primary electrode of the thyratron for supplying a negative control current at the instant of ignition.

By using an electrical or electromagnetic energy storage means, very simple switching arrangements can be provided for switching the thyratron to its blocked condition at the instant of ignition.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FGURE 1 shows, in schematic, an ignition system designed according to the present invention.

FIGURE 2 is a circuit schematic showing the elec` trical circuit diagram of the ignition system of FIGURE l.

FIGURES 3 to 7 are circuit schematics showing several further embodiments of the invention.

Referring to the figures of the drawings, FlGURE l shows a coil ignition system for operating a four cylinder, four-cycle internal combustion engine. The System includes a distributor 1i), incorporating a circuit breaker, an ignition coil 11 and a switching device 12. Four ignition wires 14 leading from the distributor 10 are connected to respective spark plugs 13, and a storage battery 15' supplies current to the system. Such storage batteries are usually rated at about 12.6 volts.

By closing an ignition switch 16, the positive lead 17 of the switching device 12 can be connected with the positive pole of the battery 15. Switching device 12 contains a silicon thyristor 2G of the pnpn-type, the anode 21 of which is connected through a compensating resistor 22 of about 0.5 to 2 ohms, to the primary winding 23 of ignition coil 11. The cathode 24, which is connected with the exteriorly located n-Zone on the silicon body of the thyratron, is connected directly to ground. A semiconductor diode 26 in parallel with a resistor 27 is connected to the control electrode 25 of the thyratron, and to control line 23, leading to the stationary contact 29 of the circuit breaker provided in distributor 10. The armature 30 of this circuit breaker is lifted off stationary contact 29 twice during each revolution of the engine by means of a cam 32 coupled with the rotating distributor ar-m 31.

A tank circuit comprising a capacitor 36 and a choke coil 35, in parallel with a Zener diode 37, is connected between the positive lead 17 and, through a resistor 31tto control line 2S. The choke 3S has an iron core 38, and an inductance of about 0.5 mh. acts as an energy storage means.

After the switch 16 is closed, the thyratron 20 allows a magnetizing current to ilow through the primary coil 23 as soon as armature 30 contacts the stationary contact 29 since this allows a positive control current to flow in the circuit comprising choke 35, resistor 34 and resistor 27. The magnetizing current in the choke coil 35, limited in magnitude by resistor 34, produces a magnetic lield in the iron core 38 of the choke. The energy of this magnetic eld is used to block the thyratron 20 as soon as the armature 30 has lifted from Contact 29; this substantially cuts the magnetizing current formerly present. Then, as a consequence of the inductance of choke 35, an inductive voltage peak is generated; this leads to a state in which the control line 23, which has been disconnected from ground, as well as resistor 27 and rectifier 26, connected to this line, are placed at a negative potential with respect to ground. The capacitor 36, connected in parallel with the choke 35, is designed with a value such that, at the instant of charge transfer which occurs at the moment of interruption, an oscillation arises the first negative half- Wave of which switches the thyratron into its blocked condition. This blocked condition, however, lasts only as long as the negative half-wave. During the subsequent opposite charge transfer process of the stored energy from capacitor 36 to the choke 35', thyratron 20 automatically returns to its original conductive condition.

The Zener diode Ylimits the control voltage whichis produced atY choke 35 'and which is increased by the resonance effect of the parallel-connected capacitor 36, to a maximum value which can not damage the `control electrode of the thyratron 20. By providing a breaker capacitor 39, which is customarily used in battery ignition systems, and which is here connected in parallel with the anode-cathode path of thyratron 2G, the shape of the ignition waveform can be improved in the conventional manner. l

In the case of the second embodiment, illustrated in FIGURE 3, "a resonance effect is achieved in the energy storage circuit comprising th'e choke 35 and capacitor 36. Thus, an increase in the control voltage for thyristor 20, 'generated at the instant the circuit breaker 29, 3i) opens, is achieved. This increase allows a design in which the choke 35 may be relatively small in structural size. In contradistinction to the embodiment previously described, in FIGURE 3 (wherein identical or identically operating components are designated by the same reference numerals as in FIGURE 2) the stationary breaker contact 29 is Connected 'to the positive lead 17, and the choke 35 is provided in a circuit connected in parallel with the control path of the thyratron 20. This has the advantage of preventing current from positive line 17 from flowing in the'choke y35 when the breaker 29, 30, is opened; it also prevents current from owing to resistor 27 inserted in the lead line to the control electrode of the thyratron, insuring that the choke produces a high inductive voltage peak at the .moment of ignition. At the instant when thyratron 20 is switched off, the diode 26 insures that the inductive switching-off voltage at choke 35 is fully effective at the control electrode. However, the value of the switching-olf voltage is limited, just as in the case of the embodiment of FIGURES 1 and 2, by a Zener diode 37 and a further diode 40 connected in series with it. Diode 40 insures that the Zener diode 37 becomes conductive only during the negative half-cycles of the control voltage.

The embodiment of FIGURE 4 shows a particularly simple circut since only a capacitor42, inserted in the lead connecting control electrode 25 of the thyratron to the stationary Contact 29 of the breaker, is used as an energy storage means for switching off the thyratron 20. A relatively high resistance 43 is connected between contact 29 and line 17;

When the breaker arm 30, which is connected to ground, leaves contact 29, the capacitor 42 is charged by a positive current pulse owing through resistor 43, control electrode 25 and cathode 24, switching on the thyratron 20. The thyratron then remains conductive until, at the instant when the breaker 29, 30, is closed, the positively charged electrode of capacitor 42 is connected directly to ground, negatively biassing the control electrode 25 and thereby blocking the thyratron 20. A special advantage of this embodiment lies in the fact that the thyratron is made conductive at each opening of the circuit breaker and is switched into its blocked state only when breaker 29, 30, closes.

In the embodiment of FIGURE 5, the capacitor 42 has the same effect as in the above-described embodiment; however, it is connected between the breaker arm and the junction point of resistor 26 and diode27. Stationary contact 29 is connected to the positive line 17. A resistor 45 is connectedbetween the breaker arm 30 and the ground yline 44. When the circuit breaker 29, 30, isv closed,

the capacitor 42 is charged. Its charging current, which iows through resistor 26 and control electrode 25, places the thyratron 2l) in its conductive state. As the instant when circuit breaker 29, 30,`opens, which happens at the instant of ignition, the capacitor 42is connected in series with the cathode of the thyratron via resistor 45. Capacitor 42 can then discharge through the control electrode 25 and the kdiode 27, and the discharge current so produced blocks the thyratron.

`In the embodiments illustrated in FIGURES 4 and 5, which contain only a single control capacitor 42, diiculties can arise when the thyratron 2t? is switched on and oft, if the battery 15 has a voltage ot less than 6 volts. In the embodiment illustrated in FIGURE 6, both a control capacitor 42 and a parallel resonant circuit,;such as is described in connection with FIGURES 2 and 3, comprising a choke 35 and a capacitor 36, are provided. The inductance of choke 35 can be lower, in the embodiment of FIGURE 6, than that in those shown in FIGURES 2 and 3.

In the embodiment shown in FIGURE 7, the circuit arrangement of the thyratron 20 'and resistor 27 (provided in the control circuit of the thyratron in parallel with rectifier 26), as well as the tank circuit comprising choke 35 and capacitor 36, corresponding to the embodiment of FIGURE 3. In this embodiment, however, a contactless circuit breaker is provided in place of the cam-actuated mechanical circuit breaker 29, 30. This contactless circuit breaker includes two transistors 50 and 51. Transistor 51 is connected through emitter resistor 52 to the positive lead 17, in such a manner that in its conductive state, it provides a magnetizing current through the choke 35 and a positive control current which switches thyratron 2t) into its conduc-tive state. This transistor is switched into cut-off, thereby triggering the ignition process, when the two permanent magnets 55 and 56, which may be mounted on a rotating disc 54 (shown in phantom lines) pass by a semiconductor resistor 57. The forward resistance of resistor 57 increases by a factor of 10 to 15 under the iniluence of the magnetic iield indicated by arrows when the magnets reach the ignition position illustrated in FIG- URE 7. The semiconductor resistor 57 is connected .in the base circuit of transistor k50, the emitter of which is directly connected to the positive lead 17.`A resistor 58 is connected between the base of transistor 50 and ground; the resistance of this resistor is great enough to maintain transistor 50 in cut-oft until the magnets have reached their illustrated position. At that instant, transistor 5t) becomes conductive and thus switches transistor 51' into cut-off; the latter then interrupts the magnetizing current in choke 35 and, as described above in connection with FIGURE 3, blocks the thyratron 20.

The control disc 54, on which magnets 55 and 56 are mounted, can be provided in a conventional distributor housing 10, if desired, together With the two switching transistors 50 and 51.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of systems differing from the types described above.

While the invention has been illustrated and described as embodied in relation to a specic engine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of the prior art, fairly constitute essential features yof the generic or specc aspects of ,this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A high-voltage ignition arrangement for an internal combustion engine comprising, in combination, an ignition coil having a primary winding and a secondary winding for providing a high-voltage ignition pulse; a direct-current source having one pole connected to said primary winding; a controlled semiconductor rectier with anode connected to said primary and secondary windings of said ignition coil, the cathode of said controlled rectifier being connected to the other pole of said direct-current source for interrupting the circuit to said primary winding, said rectifier being conductive w-hen a positive potential prevails at its control electrode and being non-conductive when a negative potential prevails at its electrode; a diode with anode connected to the control electrode of said controlled rectifier; a resistor connected in parallel with said diode; energy storage means connected between the cathode of said diode and said direct-current power source; and circuit interrupting means driven by said engine and connecting the cathode of said diode periodically to said other pole of said direct-current source, whereby said highvoltage ignition pulse is provided when said interrupting means disconnects said cathode from said direct-current source thereby initiating an oscillation terminating conduction of said controlled rectifier during the negative portion of said oscillation generated by said energy storage means.

2. The high voltage ignition arrangement as defined in claim 1 wherein said energy storage means is an induction coil with magnetizable core.

3. The high-voltage ignition arrangement as defined in claim 2 including a capacitor connected in parallel with said induction coil.

4. The high-voltage ignition arrangement as defined in claim 2 including at least one diode connected in parallel with said induction coil and having its anode connected to the negative terminal of said direct-current source.

5. The high-voltage ignition arrangement as defined in claim 4 wherein said diode connected in parallel with said induction coil is a Zener diode.

6. The high-Voltage ignition arrangement as defined in claim 2 including a limiting resistor connected in series with the parallel combination of said diode and said resistor.

7. The high-voltage ignition arrangement as defined in claim 2 including a capacitor connected between said induction coil and the parallel combination of said diode and said resistor.

8. The high-voltage ignition arrangement as defined in claim 1 wherein said energy storage means is a capacitor having one electrode connected to the parallel combination of said diode and said resistor, and having the other electrode connected to said interrupting means.

9. The high-voltage ignition arrangement as defined in claim 8 including a resistor connected between the cathode of said controlled semi-conductor rectifier and said other electrode of said capacitor.

10. The high-voltage ignition arrangement as defined in claim 1 wherein said circuit interrupting means is a cam actuated switch operated by the distributor of said internal combustion engine.

11. The high-voltage ignition arrangement as defined in claim 1 wherein said circuit interrupting means comprises a magnetic responsive resistor providing resistance varying with the intensity of the magnetic field in contact therewith; magnetic means movable past said magnetic responsive resistor for varying the magnitude of the resistance of said magnetic-responsive resistor; and a transistor connected to said magnetic-responsive resistor and actuated thereby through the variations in the resistance magnitude of said magnetic-responsive resistor resulting from the motion of said magnetic means.

References Cited UNITED STATES PATENTS 2,924,633 2/1960 Sichling et al 123-148 3,195,043 7/1965 Burig et al 324-45 3,213,320 l0/l965 Worrell 315-209 3,260,251 7/1966 Lange 123-148 OTHER REFERENCES Westinghouse, Silicon Controlled Rectifier Designers Handbook, edited by Robt. Murray, I r., pages 7-104.

JAMES D. KALLAM, Primary Examiner.

JOHN W. HUCKERT, D. O. KRAFT,

Assistant Examiners. 

1. A HIGH-VOLTAGE IGNITION ARRANGEMENT FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, IN COMBINATION, AN IGNITION COIL HAVING A PRIMARY WINDING AND A SECONDARY WINDING FOR PROVIDING A HIGH-VOLTAGE IGNITION PULSE; A DIRET-CURRENT SOURCE HAVING ONE POLE CONNECTED TO SAID PRIMARY WINDING; A CONTROLLED SEMICONDUCTOR RECTIFIER WITH ANODE CONNECTED TO SAID PRIMARY AND SECONDARY WINDINGS OF SAID IGNITION COIL, THE CATHODE OF SAID CONTROLLED RECITIFER BEING CONNECTED TO THE OTHER POLE OF SAID DIRECT-CURRENT SOURCE FOR INTERRUPTING THE CIRCUIT TO SAID PRIMARY WINDING, SAID RECTIFIER BEING CONDUCTIVE WHEN A POSITIVE POTENTIAL PREVAILS AT ITS CONTROL ELECTRODE AND BEING NON-CONDUCTIVE WHEN A NEGATIVE POTENTIAL PREVAILS AT ITS ELECTRODE; A DIODE WITH ANODE CONNECTED TO THE CONTROL ELECTRODE OF SAID CONTROLLED RECTIFIER; A RESISTOR CONNECTED IN PARALLEL WITH SAID DIODE; ENERGY STORAGE MEANS CONNECTED BETWEEN THE CATHODE OF SAID DIODE AND SAID DIRECT-CURRENT POWER SOURCE; AND CIRCUIT INTERRUPTING MEANS DRIVEN BY SAID ENGINE AND CONNECTING THE CATHODE OF SAID DIODE PERIODICALLY TO SAID OTHER POLE OF SAID DIRECT-CURRENT SOURCE, WHEREBY SAID HIGHVOLTAGE IGNITION PULSE IS PROVIDED WHEN SAID INTERRUPTING MEANS DISCONNECTS SAID CATHODE FROM SAID DIRECT-CURRENT SOURCE THEREBY INITIATING AN OSCILLATION TERMINATING CONDUCTION OF SAID CONTROLLED RECTIFIER DURING THE NEGATIVE PORTION OF SAID OSCILLATION GENERATED BY SAID ENERGY STORAGE MEANS. 